Core network interface for packet domain for uma unc applications

ABSTRACT

An UMA network controller (SGW, CM) is dedicated for an UMA mobile network comprising a CS core network (CN 2 ) and a PS core network (CN 1 ) with a SGSN. This UMA network controller comprises a security gateway (SGW) and a control means (CM) coupled one to the other. The security gateway (SGW) is arranged i) to ensure security procedures between mobile stations (MS) and the UMA world, ii) to forward messages relative to the control plan for the packet switched core network (CN 1 ) between mobile stations (MS) and the control means (CM), and iii) to forward messages relative to the user plan for the packet switched core network (CN 1 ) between mobile stations (MS) and the serving GPRS serving node (SGSN). The control means (CM) is intercalated between the security gateway (SGW) and the serving GPRS serving node (SGSN) and arranged for handling the control plan for the packet switched core network (CN 1 ).

The present invention relates to the domain of mobile (or cellular)communication networks, and more precisely to mobile communicationnetworks of the UMA (Unlicensed Mobile Access) or GAN (Generic AccessNetwork) type, notably defined by the technical specifications of the3GPP TS 43.318 v6.4.0, “Generic access to the A/Gb interface—stage 2”(release 6), and TS 44.318 v6.3.0—“Generic Access (GA) to the A/Gbinterface, Mobile GA interface layer 3 specification” (Release 6).

As it is known by the man skilled in the art, an UMA network mustcomprise UMA access node called UNC (UMA Network Controller) tointerface with serving GPRS support node(s) (SGSN) belonging to itspacket switched (PS) core network and also with mobile switchingcenter(s) (MSC) belonging to its circuit switched (CS) core network and.

In order a mobile station could exchange data with the UMA network, apermanent TCP (Transmission Control Protocol) connection must beestablished with an UNC, through which the CS and PS protocols aresupported, after an authorization phase. Since a TCP connection isnatively a transport connection oriented protocol, an UNC is astandalone machine supporting altogether CS and PS services, accordingto the 3GPP UMA standard.

From a network topology perspective, an UNC is comparable to a GERAN BSC(GSM EDGE Radio Access Network Base Station Controller) as it offersaccess to a core network by means of A and Gb interfaces respectivelyfor CS and PS core network parts.

A BSC of a GERAN necessitates solid CPU capacities to handle radioresource management algorithms and plays a role of concentration node ina TDM transmission network organized with base stations (BTSs) in a starconfiguration. Therefore altogether for CPU reasons and transmissionnetwork organization, the BSCs are very justified as dedicated accessnetwork nodes.

An UMA access network having a number of specificities compared to aGERAN network, an UNC i) must have much less CPU requirements as it doesnot handle radio resource management algorithms with complex radiooptimization features, ii) is merely a protocol gateway function for theCS core network part and a forwarding machine for the PS core networkpart, and iii) supports WiFi access point through a native IP networkand therefore is not subject to any topology constraints linked to TDMtransmission network.

So, even though an UNC stands as a BSC in a GERAN model, it has littleto do with a radio communication equipment and is more a core networktype node as it is a kind of access server combined with a protocolrelay and a traffic forwarder.

So, the object of this invention is to improve the situation byproviding for an improved core network interface for packet domain.

For this purpose, it provides an UMA network controller (UNC) for an UMAmobile communication network comprising a circuit switched core networkand a packet switched core network with at least one serving GPRSserving node (SGSN).

This UMA network controller (UNC) is characterized in that it comprisesa security gateway (SGW) and a control means coupled one to the other.

The SGW is arranged i) to ensure security procedures between mobilestations and the UMA world, ii) to forward messages relative to thecontrol plan for at least the packet switched core network betweenmobile stations and the control means, iii) to forward messages relativeto the user plan for at least the packet switched core network betweenmobile stations and the serving GPRS serving node (SGSN).

The control means is intercalated between the SGW and the SGSN andarranged for handling the control plan for at least the packet switchedcore network.

The UMA network controller according to the invention may includeadditional characteristics considered separately or combined, andnotably:

-   -   it further comprises a media gateway (MGW) coupled to its SGW        and to the circuit switched core network, and its SGW may be        further arranged i) to forward messages relative to the control        plan for the circuit switched core network between mobile        stations and the control means, and ii) to forward messages        relative to the user plan for the circuit switched core network        between mobile stations and the MGW. In this case the control        means is intercalated between the SGW and a mobile switching        center (MSC) and arranged i) for handling the control plan for        the circuit switched core network and discovery and registration        procedures of the mobile stations, and ii) for relaying circuit        switched call messages between the MSC and the mobile stations        through the SGW;

-   2. the control means may comprise a packet switched part coupled to    the SGSN, and a circuit switched part coupled to the MSC and to this    packet switched part and arranged for forwarding packet switched    call messages over TCP between the packet switched part and the    mobile stations through the SGW;    -   the packet switched part and the circuit switched part may be        arranged to exchange messages through at least one TCP path, or        another transport path, such as an UDP path for instance (one        means here by “transport path” a path associated to a transport        (or transmission) protocol);    -   the control means may be arranged to exchange information        elements, relative to the IP address and communication port        number of the mobile station and to the IP address and        communication port number of the SGSN, with this SGSN.

Other features and advantages of the invention will become apparent onexamining the detailed specifications hereafter and the appendeddrawings, wherein:

FIG. 1 schematically illustrates an example of a part of an UMA mobilenetwork comprising an UMA network controller according to the invention,

FIG. 2 schematically illustrates the main steps of a successful mobilestation initiated transport channel (TC) activation,

FIG. 3 schematically illustrates the main steps of a successful mobilestation initiated transport channel (TC) deactivation, and

FIG. 4 schematically illustrates the main steps of a successful SGSNinitiated transport channel (TC) activation.

The appended drawings may not only serve to complete the invention, butalso to contribute to its definition, if need be.

In the following description it will be considered that the mobilenetwork is of the GPRS type and comprises an UMA core network.

As it is schematically illustrated in FIG. 1, an UMA mobilecommunication network comprises notably a packet switched (PS) corenetwork CN1, a circuit switched (CS) core network CN2 and at least oneUMA network controller UNC comprising a security gateway SGW, a controlmodule CM and a media gateway MGW.

The packet switched core network CN1 comprises notably at least oneserving GPRS serving node SGSN coupled to at least one UMA networkcontroller UNC. The circuit switched core network CN2 comprises notablya mobile switching center MSC coupled to the control module CM and tothe media gateway MGW.

According to the invention, the Security Gateway SGW is coupled to themedia gateway MGW and to the control module CM. It is arranged toimplement at least three main functionalities.

Its first functionality consists in ensuring the classical andwell-known security procedures (authentication, encryption andinteraction with a server AAA dedicated to authentication, authorizationand accounting) between the mobile stations MS and the UMA world.

Its second functionality consists in forwarding the URR (UMA RadioResources) and URLC (UMA Radio Link Control) messages over TCPconnection between the mobile stations MS and the control module CM. Inother words, it forwards the messages relative to the control plan forat least the packet switched core network CN1.

Its third functionality consists in forwarding the URLC messages overUDP between the mobile stations MS and at least one serving GPRS servingnode SGSN through the security gateway SGW. In other words, it forwardsthe messages relative to the user plan for the packet switched corenetwork CN1.

According to the invention, the control module CM is at least connectedto the security gateway SGW and to at least one SGSN. It has at leastone main functionality consisting in handling the control plan for atleast the packet switched core network CN1. More precisely, it handlesthe control plan for the packet switched (PS) core network CN1, throughpacket switched call messages over TCP connexions, in order to allowinterworking between URLC and BSSGP (Base Station System GPRS Protocol).So, it forwards the URLC messages over transport connexions between atleast one SGSN and the mobile stations MS through the security gatewaySGW.

It results from the above described functionalities that the controlmodule CM of the UNC handles at least all the UMA signalisation over TCP(i.e. URLC/TCP) relative to the mobile stations MS for the packetswitched core network CN1, while the SGSN handles the UMA user plan overUDP (i.e. URLC/UDP) for the packet switched core network CN1.

According to the invention the user plan (URLC) extends up to the SGSN(in other words URLC/UDP ends into (or is running into) SGSN). So asignalisation support is required onto the control plane of the Gbinterface. For this purpose the invention proposes to adapt thewell-known Gb interface (between an UNC and a SGSN) in order to define anew interface hereafter called Gb⁺. More precisely, the Gb⁺ interface isthe Gb interface enriched with information elements essential toexchange the addresses and port numbers of the IP endpoints (as will bedetailed below).

As it is illustrated in FIG. 1, this Gb⁺ interface can be seen as twosub-interfaces: a first one called Gb⁺-1 defined between the controlmodule CM and the SGSN and dedicated to the PS control plan and a secondone Gb⁺-2 defined between the SGW and the SGSN and dedicated to the PSuser plan.

The SGW is further arranged to perform two additional functionalitieswhich are not concerned by the invention.

The first additional functionality consists in forwarding the circuitswitched data (such as voice over IP) between the mobile stations MS andthe media gateway MGW. In other words, it forwards the messages relativeto the user plan for the circuit switched core network CN2.

The second additional functionality consists in forwarding messagesrelative to the control plan for the circuit switched core network CN2between the mobile stations MS and the control module CM.

So, the control module CM also further handles the control plan for thecircuit switched core network CN2. In other words, it relays the circuitswitched call messages between the mobile switching center MSC and themobile stations MS through the security gateway SGW.

As it is illustrated in FIG. 1, the control module CM may comprise apacket switched part P1 (or UNC-PS) coupled to the SGSN, and a circuitswitched part P2 (or UNC-CS) coupled to the packet switched part P1 (andalso to the MSC).

The packet switched part P1 implements every above mentioned PSfunctionalities.

The circuit switched part P2 implements every above mentioned CSfunctionalities and an additional one consisting in forwarding the URLCpacket switched call messages over transport connexions between thepacket switched part P1 and the mobile stations MS through the SGW. Inother words, it forwards the messages relative to the control plan forthe packet switched core network CN1.

The packet switched part P1 and the circuit switched part P2 may bearranged to exchange messages through at least one TCP path, or anothertransport path, such as an UDP path for instance (one means here by“transport path” a path associated to a transport (or transmission)protocol).

When the control module CM comprises a packet switched part P1 and acircuit switched part P2, the transport (or transmission) protocol usedbetween these parts P1 and P2 may be TCP or UDP, for instance.

As mentioned before, the invention proposes a Gb⁺ interface defined froma well-known Gb interface enriched with information elements essentialto exchange the addresses of the IP endpoints and more precisely the IPaddresses (IP@) and UDP port numbers. These information elements arepreferably exchanged through Packet Flow Control (PFC) messages (requestand acknowledgment).

Reference is now made to FIG. 2 to describe the main steps of a nonlimiting example of a successful transport channel (TC) activationinitiated by a mobile station MS.

A TC activation may be performed according to one of three modes: afirst one comprising a Gb⁺ separate micro flow negotiation and a TCbinding, a second one comprising a Gb⁺ concatenated resource reservationand a TC binding, a third one comprising only a TC binding.

When a mobile station MS wants to activate a transport channel (TC), itgenerates a classical activation request, in a first step F1. Thisrequest is a message such as “URLC-Activate-UTC-REQ” whose parametersare the signalling address for communication between the mobile stationMS and a SGSN (TLLI—Temporary Logical Link Identifier) and the UDP portnumber of the mobile station (MS UDP port). This message is transmittedto the SGW by the concerned mobile station MS, and the SGW forwards itto the control module CM of its UNC.

At this stage the mobile station MS is in an URLC standby state.

Then in a second step F2 the control module CM (and more precisely itscircuit switched part P2 (or UNC-CS) if it exists) transforms(encapsulates) the received URLC activation request in an UPPSactivation request. For instance this request is a message such as“UPPS-Activate-UTC-REQ” whose parameters are the ones contained into theURLC request (TLLI and MS UDP port) and additional ones (IMSI, LAI, RAC,UMAN cell ID and MS IP@).

It is recalled that:

-   -   IMSI means International Mobile Subscriber Identity,    -   LAI means Location Area Identification (defined in the technical        specification TS 24.008 of the 3GPP),    -   RAC means Routing Area Code,    -   UMAN means UMA Network    -   MS IP@ means IP address of the mobile station.

The circuit switched part P2 (or UNC-CS) transmits this message to theassociated packet switched part P1 (or UNC-PS).

When the packet switched part P1 (or UNC-PS) receives an encapsulatedURLC message from the circuit switched part P2 (or UNC-CS), a PS contextattached to the mobile station MS is either created or updated withlocation information. Then it stores in the mobile station contextseveral information contained into the received message: the IMSI, theUMAN Cell Identity, the Routing Area Identity (which is theconcatenation of the UMAN Location Area Identification and the UMANRouting Area Code) and the TLLI.

In a third step F3 the packet switched part P1 generates a Packet FlowControl (PFC) message intended for the SGSN to which it is coupled to.For instance this message is a “Download-BSS-PFC” message whoseparameters are the TLLI contained into the received UPPS request and thePacket Flow Identifier (PFI, which is set to 1). PFI is set to 1 inorder to differentiate the UMA case from a classical case (with adedicated message this field would be omitted). This message is intendedfor creating an UMA transport channel (TC) between the mobile station MSand the packet switched core network CN1.

The packet switched part P1 (or UNC-PS) transmits this PFC message tothe SGSN.

Then the SGSN creates the required UMA transport channel (TC) andgenerates, in a fourth step F4, a new PFC message for transmitting itsinformation elements. For instance this PFC message is a“Create-BSS-PFC” message comprising the SGSN information elements toexchange (SGSN IP address (IP@) and SGSN UDP port number (UDP port)),and the parameters (TLLI, IMSI, PFI=1, PFT, ABQP), where PFT meansPacket Flow Timer and ABQP means Aggregate BSS QoS Profile. PFT is usedto configure the transport channel inactivity timer in UMA (the UNCsends an URR REGISTER UPDATE DOWNLINK message to the mobile station MSif the timer value has changed from the value given at registration).

The SGSN transmits this PFC message to the control module CM and moreprecisely to its packet switched part P1 (or UNC-PS).

In a fifth step F5 the packet switched part P1 (or UNC-PS) activates theUMA transport channel (TC) and generates a new PFC message fortransmitting the information elements of the mobile station MS whichrequired this UMA transport channel (TC) activation to the SGSN. Forinstance this PFC message is a “Create-BSS-PFC-ACK” message comprisingthe mobile station information elements to exchange (MS IP address (MSIP@) and MS UDP port number (MS UDP port)), and the parameters (TLLI,IMSI, PFI=1, PFT, ABQP).

Then in a sixth step the packet switched part P1 (or UNC-PS) generatesan UPPS message for transmitting the received SGSN information elementsto the associated circuit switched part P2 (or UNC-CS). For instancethis request is a message such as “UPPS-Activate-UTC-ACK” comprising theSGSN information elements to exchange (SGSN IP address (SGSN IP@) andSGSN UDP port number (SGSN UDP port)), and the parameters (TLLI, IMSI,cause).

In a seventh step F7 the circuit switched part P2 (or UNC-CS) transformsthe received UPPS message in an URLC message for transmitting thereceived SGSN information elements to the mobile station MS through theSGW. This request is a message such as “URLC-Activate-UTC-ACK”comprising the SGSN information elements to exchange (SGSN IP address(SGSN IP@) and SGSN UDP port number (SGSN UDP port)), and the parameters(TLLI, cause). Then the SGW forwards this URLC message to the concernedmobile station MS.

After this seventh step F7 the transport channel (TC) is bound. So themobile station MS and the SGSN may exchange data over the user plan.

For instance in an eighth step F8 the mobile station MS generates anURLC message for transmitting data to the SGSN through the SGW and thesecond part Gb⁺-2 of the Gb⁺ interface, dedicated to the PS user plan.This message is an URLC message over UDP such as “URLC-UNITDATA”comprising the parameters (TLLI, sequence number, QoS, PFI, LLC PDU).Its is recalled that LLC PDU means Logical Link Control Packet DataUnit.

For instance in a ninth step F9 the SGSN generates an URLC message fortransmitting data to the mobile station MS through the second part Gb⁺-2of the Gb⁺ interface and the SGW. This message is such as“URLC-UNITDATA” with parameters (TLLI, sequence number, QoS, PFI, LLCPDU).

It is important to notice that in the first mode (Gb⁺ separate microflow (PDP) negotiation and TC binding) the mobile station MS mustrequest GPRS service before carrying out the first step F1, i.e. beforethe mobile station MS asks the UMA WLAN bearer to transport all thesePDPs in a transport channel (TC). For this purpose it has to ask for asmany PDP contexts as necessary. So the following steps have to becarried out n times when n PDP contexts are required.

In a first step the mobile station MS sends to the SGSN a message suchas “ACTIVATE PDP CTXT REQ (QoS)” defined by the technical specificationof the 3GPP TS 24.008. Then, in a second step, the SGSN checks andnegotiates the resources and the QoS with the BSS/UNC by means of amessage such as “Create-BSS-PFC (PFI, PFT, ABQP)” defined by thetechnical specification of the 3GPP TS 48.018. And in a third step theSGSN sends a PDP context activation acknowledgement to the mobilestation MS by means of a message such as “ACTIVATE PDP CTXT ACK (QoS,PFI)” defined by the technical specification of the 3GPP TS 24.008.

In this first mode, ABQP may be either omitted or, for instance, set tothe value of the sum of the previously negotiated ABQP, in steps F4 andF5.

In the second mode (Gb⁺ concatenated resource reservation and TCbinding) the mobile station MS must request GPRS service before carryingout the first step F1, i.e. before the mobile station MS asks the UMAWLAN bearer to transport all these PDPs in a transport channel (TC). Forthis purpose it has to ask for as many PDP contexts as necessary. So thefollowing steps have to be carried out n times when n PDP contexts arerequired.

In a first step the mobile station MS sends to the SGSN a message suchas “ACTIVATE PDP CTXT REQ (QoS)” defined by the technical specificationof the 3GPP TS 24.008. Then, in a second step, the SGSN just notes therequested resources and QoS, and sends a PDP context activationacknowledgement to the mobile station MS by means of a message such as“ACTIVATE PDP CTXT ACK (QoS, PFI)” defined by the technicalspecification of the 3GPP TS 24.008.

In this second mode, ABQP is set to the value of the sum of thepreviously negotiated ABQP, in steps F4 and F5.

In the third mode (only TC binding) the mobile station MS must requestGPRS service before carrying out the first step F1, i.e. before themobile station MS asks the UMA WLAN bearer to transport all these PDP ina transport channel (TC). For this purpose it has to ask for as many PDPcontexts as necessary. So the following steps have to be carried out ntimes when n PDP contexts are required.

In a first step the mobile station MS sends to the SGSN a message suchas “ACTIVATE PDP CTXT REQ (QoS)” defined by the technical specificationof the 3GPP TS 24.008. Then, in a second step, the SGSN sends a PDPcontext activation acknowledgement to the mobile station MS by means ofa message such as “ACTIVATE PDP CTXT ACK (QoS, PFI)” defined by thetechnical specification of the 3GPP TS 24.008.

In this third mode, ABQP and PFT are omitted in steps F4 and F5.

It is also important to notice that dedicated messages could be usedinstead of the messages used in steps F4 and F5.

Reference is now made to FIG. 3 to describe the main steps of a nonlimiting example of a successful transport channel (TC) deactivationinitiated by a mobile station MS.

When a mobile station MS wants to deactivate an UMA, it generates aclassical transport channel (TC) deactivation request, in a first stepF1. This request is a message such as “URLC-Deactivate-UTC-REQ” whoseparameters are the signalling address for communication between themobile station MS and a SGSN (TLLI) and the cause. This message istransmitted to the SGW by the concerned mobile station MS, and the SGWforwards it to the control module CM of its UNC.

Then in a second step F2 the control module CM (and more precisely itscircuit switched part P2 (or UNC-CS) if it exists) transforms(encapsulates) the received URLC deactivation request in an UPPSdeactivation request. For instance this request is a message such as“UPPS-Deactivate-UTC-REQ” whose parameters are the ones contained intothe URLC request (TLLI, cause) and additional ones (IMSI, LAI, RAC, UMANcell ID and MS IP@), where MS IP@ is the IP address of the mobilestation.

The circuit switched part P2 (or UNC-CS) transmits this message to theassociated packet switched part P1 (or UNC-PS).

In a third step F3 the packet switched part P1 generates a Packet FlowControl (PFC) message requiring deactivation of the UMA transportchannel (TC) from the SGSN to which it is coupled to. For instance thismessage may be a “Modify-BSS-PFC” message whose parameters are the TLLIcontained into the received UPPS request and the Packet Flow Identifier(PFI, which is set to 1). This message is intended for deleting an UMAtransport channel (TC) with the packet switched core network CN1.Instead of a message such as “Modify-BSS-PFC”, it is also possible touse a message such as “Delete-BSS-PFC”.

The packet switched part P1 (or UNC-PS) transmits this PFC modificationmessage to the SGSN.

Then in a fourth step F4 the SGSN generates a PFC message to acknowledgereceipt of the PFC modification message and signalling that it hasproceed to the required deactivation. For instance this PFCacknowledgement message is a “Modify-BSS-PFC-ACK” message comprising theparameters (TLLI, IMSI, PFI=1, PFT). Instead of a message such as“Modify-BSS-PFC-ACK”, it is also possible to use a message such as“Delete-BSS-PFC-ACK”.

The SGSN transmits this PFC message to the control module CM and moreprecisely to its packet switched part P1 (or UNC-PS).

In a fifth step F5 the packet switched part P1 (or UNC-PS) generates anUPPS acknowledgement message to signal that the deactivation has beencarried out by the SGSN. For instance this is a message such as“UPPS-Deactivate-UTC-ACK” comprising the parameters (TLLI, IMSI).

In a sixth step F6 the circuit switched part P2 (or UNC-CS) transformsthe received UPPS acknowledgement message in an URLC acknowledgementmessage intended for the mobile station MS. This URLC acknowledgementmessage is “URLC-Deactivate-UTC-ACK” comprising the parameter TLLI. Thenthe SGW forwards this URLC acknowledgement message to the concernedmobile station MS.

Reference is now made to FIG. 4 to describe the main steps of a nonlimiting example of a successful transport channel (TC) activationinitiated by a SGSN.

When a SGSN wants to activate an UMA transport channel (TC) with amobile station MS, it generates, in a first step F1, a new PFC messagefor transmitting its own information elements and creating a downlinkLLC PDU. For instance this PFC message is a “Create-BSS-PFC” messagecomprising the SGSN information elements to exchange (SGSN IP address(IP@) and SGSN UDP port number (UDP port)), and parameters (TLLI, IMSI,PFI=1, PFT, ABQP).

The SGSN transmits this PFC message to the control module CM and moreprecisely to its packet switched part P1 (or UNC-PS).

In a second step F2 the packet switched part P1 (or UNC-PS) generates anUPPS activation message for requiring an UMA transport channel (TC)activation and transmitting the received SGSN information elements tothe associated circuit switched part P2 (or UNC-CS). For instance thisrequest is a message such as “UPPS-Activate-UTC-REQ” comprising the SGSNinformation elements to exchange (SGSN IP address (SGSN IP@) and SGSNUDP port number (SGSN UDP port)), and the parameters (TLLI, IMSI).

In a third step F3 the circuit switched part P2 (or UNC-CS) transformsthe received UPPS activation message in an URLC activation message forrequiring the UMA transport channel (TC) activation and transmitting thereceived SGSN information elements to the mobile station MS through theSGW. This request is a message such as “URLC-Activate-UTC-REQ”comprising the SGSN information elements to exchange (SGSN IP address(SGSN IP@) and SGSN UDP port number (SGSN UDP port)), and the parameterTLLI. Then the SGW forwards this URLC message to the concerned mobilestation MS.

When it receives this URLC message the mobile station MS generates, in afourth step F4, an activation request to acknowledge receipt of the URLCactivation message and transmit to the SGSN its UDP port number and theTLLI. This request is a message such as “URLC-Activate-UTC-REQ” whoseparameters are the information elements TLLI (Temporary Logical LinkIdentifier) and UDP port number (MS UDP port) of the mobile station, andthe cause. This message is transmitted to the SGW by the concernedmobile station MS, and the SGW forwards it to the control module of itsUNC.

Then in a fifth step F5 the control module CM (and more precisely itscircuit switched part P2 (or UNC-CS) if it exists) transforms(encapsulates) the received URLC activation acknowledgement in an UPPSactivation acknowledgement. For instance this acknowledgement is amessage such as “UPPS-Activate-UTC-ACK” whose parameters are the onescontained into the URLC request (TLLI, MS UDP port and cause) andadditional ones (IMSI, LAI, RAC, UMAN cell ID and MS IP@), where MS IP@is the mobile station IP address (information element).

The circuit switched part P2 (or UNC-CS) transmits this UPPS activationacknowledgement to the associated packet switched part P1 (or UNC-PS).

In a sixth step F6 the packet switched part P1 generates a Packet FlowControl (PFC) message to acknowledge the creation of the UMA transportchannel (TC). For instance this message is a “CREATE-BSS-PFC-ACK”message whose parameters are the information elements TLLI, MS IP@ andMS UDP port of the mobile station MS, contained into the received UPPSactivation acknowledgement and the Packet Flow Identifier (PFI, which isset to 1), IMSI, PFT and ABQP.

After this sixth step F6 the transport channel is bound. So the mobilestation MS and the SGSN may exchange data over the user plan.

For instance in a seventh step F7 the mobile station MS generates anURLC message for transmitting data to the SGSN through the second partGb⁺-2 of the Gb⁺ interface, dedicated to the PS user plan, and the SGW.This message is such as “URLC-UNITDATA” with parameters (TLLI, sequencenumber, QoS, PFI, LLC PDU).

It is also important to notice that dedicated messages could be usedinstead of the messages used in steps F1 and F6.

For instance when the control module CM comprises a packet switched partP1 and a circuit switched part P2, all messages between the packetswitched part P1 and the circuit switched part P2, corresponding to URRor URLC messages, contain a header (for instance encoded in “V” (fixed)format), few specific mandatory information elements with fixed length(for instance also encoded in V format), and other specific informationelements (for instance encoded in TLV format).

The two parts (control module CM and SGW) defining the UMA networkcontroller UNC according to the invention, may be realized with softwaremodules, or hardware modules, or else a combination of hardware andsoftware modules.

The invention is not limited to the embodiments of UMA networkcontroller described above, only as examples, but it encompasses allalternative embodiments which may be considered by one skilled in theart within the scope of the claims hereafter.

1. UMA network controller (SGW, CM) for an UMA mobile communicationnetwork comprising a circuit switched core network (CN2) and a packetswitched core network (CN1) with at least one serving GPRS serving node(SGSN), characterized in that it comprises a security gateway (SGW) anda control means (CM) coupled one to the other, said security gateway(SGW) being arranged i) to ensure security procedures between mobilestations (MS) and an UMA world, ii) to forward messages relative to thecontrol plan for said packet switched core network (CN1) between mobilestations (MS) and said control means (CM), and iii) to forward messagesrelative to the user plan for the packet switched core network (CN1)between mobile stations (MS) and said serving GPRS serving node (SGSN),and said control means (CM) being intercalated between said securitygateway (SGW) and said serving GPRS serving node (SGSN) and arranged forhandling the control plan for the packet switched core network (CN1). 2.UMA network controller according to claim 1, characterized in that itfurther comprises a media gateway (MGW) coupled to said security gateway(SGW) and to said circuit switched core network (CN2), in that saidsecurity gateway (SGW) is further arranged i) to forward messagesrelative to the control plan for said circuit switched core network(CN2) between mobile stations (MS) and said control means (CM), and ii)to forward messages relative to the user plan for the circuit switchedcore network (CN2) between mobile stations (MS) and said media gateway(MGW), and in that said control means (CM) is intercalated between saidsecurity gateway (SGW) and a mobile switching center (MSC) of saidcircuit switched core network (CN2) and arranged i) for handling thecontrol plan for said circuit switched core network (CN2) and discoveryand registration procedures of said mobile stations (MS), and ii) forrelaying circuit switched call messages between said mobile switchingcenter (MSC) and said mobile stations (MS) through said security gateway(SGW).
 3. UMA network controller according to claim 2, characterized inthat said control means comprises i) a packet switched part (P1) coupledto said serving GPRS serving node (SGSN) and ii) a circuit switched part(P2) coupled to said mobile switching center (MSC) and to said packetswitched part (P1) and arranged for forwarding packet switched callmessages over TCP between said packet switched part (P1) and said mobilestations (MS) through said security gateway (SGW).
 4. UMA networkcontroller according to claim 3, characterized in that said packetswitched part (P1) and circuit switched part (P2) are arranged toexchange messages through at least one transport path.
 5. UMA networkcontroller according to claim 4, characterized in that said transportpath is chosen in a group comprising at least a TCP path and an UDPpath.
 6. UMA network controller according to claim 1, characterized inthat said control means (CM) is arranged to exchange informationelements, relative to the IP address and communication port number of amobile station (MS) and to the IP address and communication port numberof said serving GPRS serving node (SGSN), with said serving GPRS servingnode (SGSN).